The apps don't have to deal with it. It's a read error. Presumably something they already deal with. There's no operational difference for the end user between

The apps don't have to deal with it. It's a read error. Presumably something they already deal with. There's no operational difference for the end user between a block that can't be read and a block than can be read but with corrupted data. And yes, storage would ideally be paired with another physical device to provide redundancy and a mechanism to correct the error on the erroring device.